Address review comments

.agents/codebase-insights.txt: 
ci/test/python-recorder-smoke.sh: 
src/ct/trace/record.nim: 

Signed-off-by: Tzanko Matev <[email protected]>

Author: tzanko-matev

.agents/codebase-insights.txt

@@ -22,5 +22,6 @@
   is always terminated when the app exits.
 - `ct record` now prefers `CODETRACER_PYTHON_INTERPRETER`, `PYTHON_EXECUTABLE`, `PYTHONEXECUTABLE`, or PATH resolution to locate the Python runtime before delegating to the db backend, and `db-backend-record` expects the resolved interpreter via `--python-interpreter` when launching the recorder.
 - `ct record` resolves Python via env vars (`CODETRACER_PYTHON_INTERPRETER`, `PYTHON_EXECUTABLE`, `PYTHONEXECUTABLE`, `PYTHON`) before checking PATH. When falling back to PATH we now call `findExe(..., followSymlinks=false)` so virtualenv launchers keep their original location and `pyvenv.cfg` remains discoverable.
+- Interpreter overrides (e.g. `CODETRACER_PYTHON_INTERPRETER`) are now treated as authoritative; if the configured path cannot be resolved we error instead of silently falling back to PATH.
 - `ct record` verifies that `codetracer_python_recorder` is importable before launching the db backend and prints actionable guidance if the module is missing or broken.
 - Sudoku test-program datasets include intentionally invalid boards (e.g., examples #3 and #6) with duplicate digits inside a sub-grid; solvers should detect and report these gracefully.

ci/test/python-recorder-smoke.sh

@@ -136,14 +136,14 @@ if [[ ${INTERP_STATUS} -eq 0 ]]; then
   exit 1
 fi
 
-if ! grep -q "Python module \`codetracer_python_recorder\` is not installed for interpreter" <<<"${MISSING_INTERP_OUTPUT}"; then
-  echo "error: missing interpreter output did not mention missing interpreter"
+if ! grep -q "CODETRACER_PYTHON_INTERPRETER is set" <<<"${MISSING_INTERP_OUTPUT}"; then
+  echo "error: missing interpreter output did not explain which override failed"
   echo "${MISSING_INTERP_OUTPUT}"
   exit 1
 fi
 
-if ! grep -q "CODETRACER_PYTHON_INTERPRETER" <<<"${MISSING_INTERP_OUTPUT}"; then
-  echo "error: missing interpreter output did not reference CODETRACER_PYTHON_INTERPRETER hint"
+if ! grep -q "does not resolve to a Python interpreter" <<<"${MISSING_INTERP_OUTPUT}"; then
+  echo "error: missing interpreter output did not describe the resolution failure"
   echo "${MISSING_INTERP_OUTPUT}"
   exit 1
 fi

src/ct/trace/record.nim

@@ -46,8 +46,9 @@ proc resolveInterpreterCandidate(candidate: string): string =
 
   ""
 
-proc resolvePythonInterpreter(): string =
+proc resolvePythonInterpreter(): tuple[path: string, error: string] =
   ## Resolve the Python interpreter by inspecting common environment variables and PATH.
+  ## Authoritative overrides (env vars) must point to a valid interpreter; otherwise we surface the failure.
   let envCandidates = @[
     "CODETRACER_PYTHON_INTERPRETER",
     "PYTHON_EXECUTABLE",
@@ -60,14 +61,18 @@ proc resolvePythonInterpreter(): string =
     if value.len > 0:
       let resolved = resolveInterpreterCandidate(value)
       if resolved.len > 0:
-        return resolved
+        return (resolved, "")
+      else:
+        let trimmedValue = value.strip()
+        let presentedValue = if trimmedValue.len > 0: trimmedValue else: value
+        return ("", fmt"{envName} is set to '{presentedValue}' but it does not resolve to a Python interpreter. Update the variable or unset it to fall back to PATH detection.")
 
   for binary in ["python3", "python", "py"]:
     let resolved = resolveInterpreterCandidate(binary)
     if resolved.len > 0:
-      return resolved
+      return (resolved, "")
 
-  ""
+  ("", "")
 
 type PythonRecorderCheckStatus = enum
   recorderPresent,
@@ -227,7 +232,10 @@ proc record*(lang: string,
     pargs.add(socketPath)
 
   if detectedLang == LangPythonDb:
-    let pythonInterpreter = resolvePythonInterpreter()
+    let (pythonInterpreter, resolverError) = resolvePythonInterpreter()
+    if resolverError.len > 0:
+      echo "error: " & resolverError
+      quit(1)
     if pythonInterpreter.len == 0:
       echo "error: Python interpreter not found. Set CODETRACER_PYTHON_INTERPRETER or ensure `python` is on PATH."
       quit(1)